linux/Documentation/perf_counter/util/symbol.c

556 lines
12 KiB
C
Raw Normal View History

#include "util.h"
#include "../perf.h"
#include "string.h"
#include "symbol.h"
#include <libelf.h>
#include <gelf.h>
#include <elf.h>
static struct symbol *symbol__new(uint64_t start, uint64_t len,
const char *name, unsigned int priv_size)
{
size_t namelen = strlen(name) + 1;
struct symbol *self = malloc(priv_size + sizeof(*self) + namelen);
if (self != NULL) {
if (priv_size) {
memset(self, 0, priv_size);
self = ((void *)self) + priv_size;
}
self->start = start;
self->end = start + len - 1;
memcpy(self->name, name, namelen);
}
return self;
}
static void symbol__delete(struct symbol *self, unsigned int priv_size)
{
free(((void *)self) - priv_size);
}
static size_t symbol__fprintf(struct symbol *self, FILE *fp)
{
return fprintf(fp, " %llx-%llx %s\n",
self->start, self->end, self->name);
}
struct dso *dso__new(const char *name, unsigned int sym_priv_size)
{
struct dso *self = malloc(sizeof(*self) + strlen(name) + 1);
if (self != NULL) {
strcpy(self->name, name);
self->syms = RB_ROOT;
self->sym_priv_size = sym_priv_size;
}
return self;
}
static void dso__delete_symbols(struct dso *self)
{
struct symbol *pos;
struct rb_node *next = rb_first(&self->syms);
while (next) {
pos = rb_entry(next, struct symbol, rb_node);
next = rb_next(&pos->rb_node);
rb_erase(&pos->rb_node, &self->syms);
symbol__delete(pos, self->sym_priv_size);
}
}
void dso__delete(struct dso *self)
{
dso__delete_symbols(self);
free(self);
}
static void dso__insert_symbol(struct dso *self, struct symbol *sym)
{
struct rb_node **p = &self->syms.rb_node;
struct rb_node *parent = NULL;
const uint64_t ip = sym->start;
struct symbol *s;
while (*p != NULL) {
parent = *p;
s = rb_entry(parent, struct symbol, rb_node);
if (ip < s->start)
p = &(*p)->rb_left;
else
p = &(*p)->rb_right;
}
rb_link_node(&sym->rb_node, parent, p);
rb_insert_color(&sym->rb_node, &self->syms);
}
struct symbol *dso__find_symbol(struct dso *self, uint64_t ip)
{
struct rb_node *n;
if (self == NULL)
return NULL;
n = self->syms.rb_node;
while (n) {
struct symbol *s = rb_entry(n, struct symbol, rb_node);
if (ip < s->start)
n = n->rb_left;
else if (ip > s->end)
n = n->rb_right;
else
return s;
}
return NULL;
}
size_t dso__fprintf(struct dso *self, FILE *fp)
{
size_t ret = fprintf(fp, "dso: %s\n", self->name);
struct rb_node *nd;
for (nd = rb_first(&self->syms); nd; nd = rb_next(nd)) {
struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
ret += symbol__fprintf(pos, fp);
}
return ret;
}
static int dso__load_kallsyms(struct dso *self, symbol_filter_t filter, int verbose)
{
struct rb_node *nd, *prevnd;
char *line = NULL;
size_t n;
FILE *file = fopen("/proc/kallsyms", "r");
if (file == NULL)
goto out_failure;
while (!feof(file)) {
__u64 start;
struct symbol *sym;
int line_len, len;
char symbol_type;
line_len = getline(&line, &n, file);
if (line_len < 0)
break;
if (!line)
goto out_failure;
line[--line_len] = '\0'; /* \n */
len = hex2u64(line, &start);
len++;
if (len + 2 >= line_len)
continue;
symbol_type = toupper(line[len]);
/*
* We're interested only in code ('T'ext)
*/
if (symbol_type != 'T' && symbol_type != 'W')
continue;
/*
* Well fix up the end later, when we have all sorted.
*/
sym = symbol__new(start, 0xdead, line + len + 2,
self->sym_priv_size);
if (sym == NULL)
goto out_delete_line;
if (filter && filter(self, sym))
symbol__delete(sym, self->sym_priv_size);
else
dso__insert_symbol(self, sym);
}
/*
* Now that we have all sorted out, just set the ->end of all
* symbols
*/
prevnd = rb_first(&self->syms);
if (prevnd == NULL)
goto out_delete_line;
for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),
*curr = rb_entry(nd, struct symbol, rb_node);
prev->end = curr->start - 1;
prevnd = nd;
}
free(line);
fclose(file);
return 0;
out_delete_line:
free(line);
out_failure:
return -1;
}
/**
* elf_symtab__for_each_symbol - iterate thru all the symbols
*
* @self: struct elf_symtab instance to iterate
* @index: uint32_t index
* @sym: GElf_Sym iterator
*/
#define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
for (index = 0, gelf_getsym(syms, index, &sym);\
index < nr_syms; \
index++, gelf_getsym(syms, index, &sym))
static inline uint8_t elf_sym__type(const GElf_Sym *sym)
{
return GELF_ST_TYPE(sym->st_info);
}
static inline int elf_sym__is_function(const GElf_Sym *sym)
{
return elf_sym__type(sym) == STT_FUNC &&
sym->st_name != 0 &&
sym->st_shndx != SHN_UNDEF &&
sym->st_size != 0;
}
static inline const char *elf_sym__name(const GElf_Sym *sym,
const Elf_Data *symstrs)
{
return symstrs->d_buf + sym->st_name;
}
static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
GElf_Shdr *shp, const char *name,
size_t *index)
{
Elf_Scn *sec = NULL;
size_t cnt = 1;
while ((sec = elf_nextscn(elf, sec)) != NULL) {
char *str;
gelf_getshdr(sec, shp);
str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
if (!strcmp(name, str)) {
if (index)
*index = cnt;
break;
}
++cnt;
}
return sec;
}
#define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
idx < nr_entries; \
++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
#define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
idx < nr_entries; \
++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
static int dso__synthesize_plt_symbols(struct dso *self, Elf *elf,
GElf_Ehdr *ehdr, Elf_Scn *scn_dynsym,
GElf_Shdr *shdr_dynsym,
size_t dynsym_idx)
{
uint32_t nr_rel_entries, idx;
GElf_Sym sym;
__u64 plt_offset;
GElf_Shdr shdr_plt;
struct symbol *f;
GElf_Shdr shdr_rel_plt;
Elf_Data *reldata, *syms, *symstrs;
Elf_Scn *scn_plt_rel, *scn_symstrs;
char sympltname[1024];
int nr = 0, symidx;
scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
".rela.plt", NULL);
if (scn_plt_rel == NULL) {
scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
".rel.plt", NULL);
if (scn_plt_rel == NULL)
return 0;
}
if (shdr_rel_plt.sh_link != dynsym_idx)
return 0;
if (elf_section_by_name(elf, ehdr, &shdr_plt, ".plt", NULL) == NULL)
return 0;
/*
* Fetch the relocation section to find the indexes to the GOT
* and the symbols in the .dynsym they refer to.
*/
reldata = elf_getdata(scn_plt_rel, NULL);
if (reldata == NULL)
return -1;
syms = elf_getdata(scn_dynsym, NULL);
if (syms == NULL)
return -1;
scn_symstrs = elf_getscn(elf, shdr_dynsym->sh_link);
if (scn_symstrs == NULL)
return -1;
symstrs = elf_getdata(scn_symstrs, NULL);
if (symstrs == NULL)
return -1;
nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
plt_offset = shdr_plt.sh_offset;
if (shdr_rel_plt.sh_type == SHT_RELA) {
GElf_Rela pos_mem, *pos;
elf_section__for_each_rela(reldata, pos, pos_mem, idx,
nr_rel_entries) {
symidx = GELF_R_SYM(pos->r_info);
plt_offset += shdr_plt.sh_entsize;
gelf_getsym(syms, symidx, &sym);
snprintf(sympltname, sizeof(sympltname),
"%s@plt", elf_sym__name(&sym, symstrs));
f = symbol__new(plt_offset, shdr_plt.sh_entsize,
sympltname, self->sym_priv_size);
if (!f)
return -1;
dso__insert_symbol(self, f);
++nr;
}
} else if (shdr_rel_plt.sh_type == SHT_REL) {
GElf_Rel pos_mem, *pos;
elf_section__for_each_rel(reldata, pos, pos_mem, idx,
nr_rel_entries) {
symidx = GELF_R_SYM(pos->r_info);
plt_offset += shdr_plt.sh_entsize;
gelf_getsym(syms, symidx, &sym);
snprintf(sympltname, sizeof(sympltname),
"%s@plt", elf_sym__name(&sym, symstrs));
f = symbol__new(plt_offset, shdr_plt.sh_entsize,
sympltname, self->sym_priv_size);
if (!f)
return -1;
dso__insert_symbol(self, f);
++nr;
}
} else {
/*
* TODO: There are still one more shdr_rel_plt.sh_type
* I have to investigate, but probably should be ignored.
*/
}
return nr;
}
static int dso__load_sym(struct dso *self, int fd, const char *name,
symbol_filter_t filter, int verbose)
{
Elf_Data *symstrs;
uint32_t nr_syms;
int err = -1;
uint32_t index;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *syms;
GElf_Sym sym;
Elf_Scn *sec, *sec_dynsym;
Elf *elf;
size_t dynsym_idx;
int nr = 0;
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
if (verbose)
fprintf(stderr, "%s: cannot read %s ELF file.\n",
__func__, name);
goto out_close;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
if (verbose)
fprintf(stderr, "%s: cannot get elf header.\n", __func__);
goto out_elf_end;
}
/*
* We need to check if we have a .dynsym, so that we can handle the
* .plt, synthesizing its symbols, that aren't on the symtabs (be it
* .dynsym or .symtab)
*/
sec_dynsym = elf_section_by_name(elf, &ehdr, &shdr,
".dynsym", &dynsym_idx);
if (sec_dynsym != NULL) {
nr = dso__synthesize_plt_symbols(self, elf, &ehdr,
sec_dynsym, &shdr,
dynsym_idx);
if (nr < 0)
goto out_elf_end;
}
/*
* But if we have a full .symtab (that is a superset of .dynsym) we
* should add the symbols not in the .dynsyn
*/
sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
if (sec == NULL) {
if (sec_dynsym == NULL)
goto out_elf_end;
sec = sec_dynsym;
gelf_getshdr(sec, &shdr);
}
syms = elf_getdata(sec, NULL);
if (syms == NULL)
goto out_elf_end;
sec = elf_getscn(elf, shdr.sh_link);
if (sec == NULL)
goto out_elf_end;
symstrs = elf_getdata(sec, NULL);
if (symstrs == NULL)
goto out_elf_end;
nr_syms = shdr.sh_size / shdr.sh_entsize;
elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
struct symbol *f;
if (!elf_sym__is_function(&sym))
continue;
sec = elf_getscn(elf, sym.st_shndx);
if (!sec)
goto out_elf_end;
gelf_getshdr(sec, &shdr);
sym.st_value -= shdr.sh_addr - shdr.sh_offset;
f = symbol__new(sym.st_value, sym.st_size,
elf_sym__name(&sym, symstrs),
self->sym_priv_size);
if (!f)
goto out_elf_end;
if (filter && filter(self, f))
symbol__delete(f, self->sym_priv_size);
else {
dso__insert_symbol(self, f);
nr++;
}
}
err = nr;
out_elf_end:
elf_end(elf);
out_close:
return err;
}
int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
{
int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
char *name = malloc(size);
int variant = 0;
int ret = -1;
int fd;
if (!name)
return -1;
more:
do {
switch (variant) {
case 0: /* Fedora */
snprintf(name, size, "/usr/lib/debug%s.debug", self->name);
break;
case 1: /* Ubuntu */
snprintf(name, size, "/usr/lib/debug%s", self->name);
break;
case 2: /* Sane people */
snprintf(name, size, "%s", self->name);
break;
default:
goto out;
}
variant++;
fd = open(name, O_RDONLY);
} while (fd < 0);
ret = dso__load_sym(self, fd, name, filter, verbose);
close(fd);
/*
* Some people seem to have debuginfo files _WITHOUT_ debug info!?!?
*/
if (!ret)
goto more;
out:
free(name);
return ret;
}
static int dso__load_vmlinux(struct dso *self, const char *vmlinux,
symbol_filter_t filter, int verbose)
{
int err, fd = open(vmlinux, O_RDONLY);
if (fd < 0)
return -1;
err = dso__load_sym(self, fd, vmlinux, filter, verbose);
close(fd);
return err;
}
int dso__load_kernel(struct dso *self, const char *vmlinux,
symbol_filter_t filter, int verbose)
{
int err = -1;
if (vmlinux)
err = dso__load_vmlinux(self, vmlinux, filter, verbose);
if (err)
err = dso__load_kallsyms(self, filter, verbose);
return err;
}
void symbol__init(void)
{
elf_version(EV_CURRENT);
}